The mechanical properties of metallic materials often degrade under harsh cryogenic conditions, posing challenges for low-temperature infrastructures1. Here we introduce a dual-scale atomic-ordering nanostructure, characterized by an exceptionally high number density of co-existing subnanoscale short-range ordering (approximately 2.4 × 1026 m-3) and nanoscale long-range ordering (approximately 4.5 × 1025 m-3) domains, within a metallic solid-solution matrix in a CoNiV-based alloy to improve the synergy of strength and ductility at low temperatures. We observe an ordering-induced increase in dislocation shear stress as well as a more rapid dislocation multiplication owing to the dislocation blocking effect of nanoscale long-range ordering and the associated generation of new dislocations. The latter effect also releases stress concentrations at nanoscale long-range-ordered obstacles that otherwise would promote damage initiation and failure. Consequently, the alloy shows a strength-elongation product of 76 GPa % with a yield strength of approximately 1.2 GPa at 87 K, outperforming materials devoid of such ordering hierarchy, containing only short-range ordered or coherent precipitates of a few tens of nanometres. Our results highlight the impact of dual co-existing chemical ordering on the mechanical properties of complex alloys and offer guidelines to control these ordering states to enhance their mechanical performance for cryogenic applications.

Solution-processed semiconductor lasers promise lightweight, wearable and scalable optoelectronic applications. Among the gain media for solution-processed lasers, metal halide perovskites stand out as an exceptional class because of their ability to achieve wavelength-adjustable, low-threshold lasing under optical pumping1-8. Despite the progress in this field, electrically driven lasing from perovskite semiconductors remains a critical challenge. Here we demonstrate an electrically driven perovskite laser, constructed by vertically integrating a low-threshold single-crystal perovskite microcavity sub-unit with a high-power microcavity perovskite LED (PeLED) sub-unit. Under pulsed electrical excitation, the dual-cavity perovskite device shows a minimum lasing threshold of 92 A cm-2 (average threshold: 129 A cm-2, at about 22 °C, in air), which is an order of magnitude lower than that of state-of-the-art electrically driven organic lasers9,10. Key to this demonstration is the integrated dual-cavity device architecture, which allows the microcavity PeLED sub-unit to deliver directional emission into the single-crystal perovskite microcavity sub-unit (at a coupling efficiency of about 82.7%) to establish the lasing action. An operational half-life (T50) of 1.8 h (6.4 × 104 voltage pulses at 10 Hz) is achieved, outperforming the stability of electrically pumped organic lasers9,10. The dual-cavity perovskite laser can be rapidly modulated at a bandwidth of 36.2 MHz, indicating its potential for data transmission and computational applications.

Haematopoietic stem cells (HSCs) reside in specialized microenvironments, referred to as niches, and the classical model suggests that HSC numbers are predominantly determined by the niche size1-5. However, the vast excess of niche cells relative to HSCs challenges this perspective. To rigorously define the role of niche size in regulating HSC numbers, we developed a femur-transplantation system, enabling us to increase available HSC niches. Notably, the addition of niches did not alter the total HSC numbers in the body, suggesting the presence of a systemic mechanism that limits HSC numbers. Additionally, HSC numbers in transplanted wild-type femurs did not exceed physiological levels when HSCs were mobilized from defective endogenous niches to the periphery, indicating that HSC numbers are constrained at the local level as well. The notion of dual restrictions at systemic and local levels was further supported by other experimental approaches, including parabiosis and non-conditioned transfer of HSCs after bone transplantation. Moreover, we found that thrombopoietin has a pivotal role in determining the total number of HSCs in the body, even in the context of increased niche availability. Our study redefines key principles underlying HSC number regulation, providing insights into this critical biological process.

The armoured ankylosaurian dinosaurs are best known from Late Cretaceous Northern Hemisphere ecosystems, but their early evolution in the Early-Middle Jurassic is shrouded in mystery due to a poor fossil record1,2. Spicomellus afer was suggested to be the world's oldest ankylosaur and the first from Africa, but was based on only a single partial rib from the Middle Jurassic of Morocco3. Here we describe a new, much more complete specimen that confirms the ankylosaurian affinities of Spicomellus, and demonstrates that it has uniquely elaborate dermal armour unlike that of any other vertebrate, extant or extinct. The presence of 'handle' vertebrae in the tail of Spicomellus indicates that it possessed a tail weapon, overturning current understanding of tail club evolution in ankylosaurs, as these structures were previously thought to have evolved only in the Early Cretaceous4. This ornate armour may have functioned for display as well as defence, and a later reduction to simpler armour with less extravagant osteoderms in Late Cretaceous taxa might indicate a shift towards a primarily defensive function, perhaps in response to increased predation pressures or a switch to combative courtship displays.

The Great Fear of 1789, a wave of panic and unrest in rural France fuelled by the spreading of rumours, was an important moment at the onset of the French Revolution, marking the collapse of feudalism and the rise of the new regime1. The Great Fear provides a vivid example of the role the spreading of rumours has in driving political changes that might be relevant today2,3. Here, we collect existing historical records related to the Great Fear and use epidemiology tools and models4 to reconstruct the network of its transmission from town to town. In this way, we quantify the spatiotemporal spread of the rumours and compute key epidemiological parameters, such as the basic reproduction number. Exploiting information on the structure of the road network in eighteenth century France5, we estimate the most probable diffusion paths of the Great Fear and quantify the distribution of spreading velocities. By endowing the nodes in our reconstructed network with indicators related to the institutional, demographic and socio-economic conditions of the time6, including literacy, population size, political participation, wheat prices7,8, income and ownership laws9, and the unequal distribution of land ownership, we compute factors associated with spread of the Great Fear. Our analysis sheds light on unresolved historiographic issues on the significance of the Great Fear for the French Revolution, providing a quantitative answer to the unresolved debate between the role of emotions and rationality in explaining its diffusion.